1. Field of the Invention
The present invention relates to an optical pickup mechanism for use in an optical recording/reproducing apparatus.
2. Description of Related Art
In a conventional rotation-type optical pickup, as illustrated in FIG. 6 of Japanese Patent Publication No. 60-30017, the optical axis of a light beam of a movable unit includes an objective lens that extends toward the outside of the movable unit along a path parallel to the rotation axis.
In the case of an optical pickup having a laser unit in a movable unit, the optical axis of a light beam is also parallel to the rotation axis, as shown in FIG. 9 of Japanese Patent Publication No. 60-30017.
On the other hand, in an optical pickup having a supporting mechanism including a parallel plate spring and a rotating hinge, as shown in FIGS. 6 and 8 of Japanese Laid-Open Patent Application No. 62-40627, only one rotating hinge is used, and the optical axis extends to the outside of a movable unit along a path parallel to the rotation axis.
There is a great need for a high-performance optical recording/reproducing apparatus that can transfer data at a high speed with a short access time. However, in a conventional rotation-type optical pickup, if a laser unit is included in a movable unit in an integral fashion to achieve a small size and light weight, the optical path must be off the rotation axis, and thus the size expands in a plane. As a result, it is impossible to reduce the weight of a movable unit.
Another problem is that if component parts are disposed asymmetrically about the axis of rotation, a weight imbalance occurs.
In a conventional rotation-type optical pickup, when it is required to increase the driving force to achieve a higher operation speed, the following known techniques are available. A first technique employs a larger coil. However, this conventional technique has a disadvantage in that the outside dimensions become greater. A second technique is to employ a thicker magnet. This technique also has disadvantages in that the outside dimensions become greater and when a magnetic circuit with no opposing yoke is used the linear range in driving force becomes narrow.